This is a randomized controlled trial of two methods of cervical preparation before second trimester surgical abortion between 15 and 18 weeks. During this period of pregnancy, cervical preparation is usual, but not uniform, and there are two methods of cervical preparation commonly used. One is the insertion of osmotic dilators, usually performed the day before the abortion, which provides primarily mechanical dilation. The other is the use of buccal or vaginal misoprostol placed one or several hours prior to abortion.

Both methods have their advocates, however they each have some disadvantages. Using mifepristone the day prior to abortion would avoid some disadvantages of osmotic dilators, including the discomfort of osmotic dilators and the need for a separate insertion procedure.

In this study we would compare mifepristone and misoprostol use to osmotic dilator use, as both are administered the day before. Mifepristone would be given 24 hours prior to abortion, and misoprostol 400 mcg would be administered buccally 2 hours prior to abortion. Osmotic dilators are the method currently used in our institution, and are placed 24 hours prior to abortion.

The primary outcome will be the length of the procedure. Secondary outcomes will include amount of dilation achieved, ease of procedure, patient assessment of discomfort after mifepristone or dilators, discomfort during the abortion procedure, acceptability to patients, and acceptability to staff.